1. Field of the Invention
The present invention relates to disk drives of the type that accept removable disk cartridges, and more particularly, to a disk drive apparatus having a mechanism for automatically loading a spindle motor, i.e., moving the spindle motor into engagement with the hub of a disk cartridge upon insertion of the disk cartridge into the drive.
2. Description of the Prior Art
Removable disk cartridges for storing digital electronic information typically comprise an outer casing or shell that houses a rotatable recording medium, or disk, upon which electronic information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. The disk is mounted on a hub that rotates freely within the cartridge. When the cartridge is inserted into a disk drive, a motor-driven spindle in the drive must engage the hub in order to rotate the disk(s) within the cartridge.
Standard floppy disk drives typically employ a mechanism that guides the disk cartridge as it is inserted into the drive, so that the hub of the disk is brought downwardly into engagement with a fixed, rotatable spindle. These drives must be of sufficient height to accommodate the vertical movement of the floppy disk. A more preferable solution is to provide a straight insertion path for the cartridge and to move the spindle motor into engagement with the hub of the cartridge.
The popular and commercially successfully Iomega ZIP.TM. drive provides a straight insertion path for its disk cartridge. Guide rails within the ZIP.TM. drive guide the cartridge straight into the drive. When the cartridge reaches a certain point during insertion, the front peripheral edge of the cartridge contacts a cartridge receiving stop on a movable platform within the drive. The spindle motor of the disk drive is mounted on the movable platform. Continued insertion of the cartridge into the drive pushes the movable platform backward. As the movable platform moves backward within the drive, the platform raises to bring the spindle motor on the platform into engagement with the hub of the disk cartridge. Additional details of this spindle motor loading mechanism are provided in co-pending application Ser. No. 08/398,576, entitled "Moveable Internal Platform for a Disk Drive".
Other prior art spindle motor loading mechanisms are described in published International Application No. WO 93/18507, U.S. Pat. No. 5,317,464 (Witt et al.) and U.S. Pat. No. 4,663,677 (Griffith et al.), the latter of which is assigned to the same Assignee as the present invention. All of these references describe removable cartridge disk drives in which the spindle motor is moved vertically into engagement with the hub of a disk cartridge upon insertion of the cartridge into the disk drive. In each case, movement of the spindle motor is effected through a complex series of mechanical linkages. The complexity of such mechanical linkages increases the manufacturing costs of these disk drives. Moreover, each of these prior art disk drives requires manual operation by the user. For example, in both U.S. Pat. No. 4,663,677 and Published International Application No. WO 93/18507, the spindle motor is brought into engagement with the disk cartridge by the manual operation of a lever disposed on the front of the drive chassis. Movement of the lever is translated into movement of the spindle motor by a series of linkages, cams and gears. In U.S. Pat. No. 5,317,464, the manual closure of a drive door is translated through a series of linkages and gears into vertical movement of the spindle motor.
U.S. Pat. No. 4,482,993 discloses a compact disk player that employs a motor driven cam member to move the spindle motor of the drive vertically into engagement with the central hub of a compact disk. The loading mechanism is not designed for use with disk cartridges of the type described above. Rather, the disclosed drive is designed to receive standard compact disks that are not contained within a cartridge housing. An opto-electronic switch detects insertion of a compact disk into the drive and activates the motor driven cam member in order to move the spindle into engagement with the disk hub. As the cam mechanism brings the spindle motor into engagement with the disk hub, the mechanism contacts a mechanical switch that deactivates the cam mechanism. Activation of an ejection button causes the motorized cam mechanism to be reactivated, thereby lowering the spindle motor.
An improved automatic spindle motor loading mechanism utilizing a motorized ring assembly is described in co-pending application Ser. No. 08/438,255, entitled "Disk Drive Having An Automatic Spindle Loading Mechanism." The mechanism described therein is employed in the popular and commercially successful Iomega JAZ.TM. drive.
High-capacity removable cartridge disk drives, such as the Iomega ZIP.TM. and JAZ.TM. drives, are becoming increasingly popular with users of desktop personal computers and workstations. Both the lomega ZIP.TM. and JAZ.TM. disk drives are presently available in an internal configuration, which can be installed in the standard drive bay of a desktop personal computer or workstation, and in an external configuration which can be connected to an external input/output port on a computer. In order to provide the functionality of such high-capacity removable cartridge disk drives in a laptop or notebook computer platform, the overall profile of the drive must be reduced to fit within the low-profile drive bays typically found on such small computers. Unfortunately, the disk drive apparatus and spindle motor loading mechanisms disclosed in the aforementioned references do not provide the reduced profiles necessary for use in laptop and notebook computers. Additionally, these prior art mechanisms are mechanically complex and increase the cost of drive manufacture. These and other disadvantages make such disk drive apparatus and spindle motor loading mechanisms impractical for use in low-profile laptop and notebook computer systems. Accordingly, there is a need for an improved disk drive apparatus and spindle motor loading mechanism that achieves a low profile and that is simple, cost effective and precise. The present invention satisfies this need.